Assuming the following parameters for a new server storage configuration:
- All drives are SSD
- Few large drives are preferred over many small drives
- RAID 1/mirroring is preferred over RAID 5/6/parity
- A dedicated hardware RAID adapter is preferred over software RAID or storage spaces
- Edit: Only one single RAID array is required
So to me it all boils down to a three drive setup with either
- 2-way RAID 1, with hot spare
- 3-way RAID 1, no hot spare
While the obvious advantages of the 3-way setup are
- Potential read performance bonus
- Concurrent loss of two drives supported
Are there any points to make in favor of the 2-way hot spare setup except maybe these?
- All data is also written to the third drive, wearing it out like just like the other two, while a hot spare won't be written to before a potential array rebuild.
- Potential write performance penalty due to all data needing to be written three times opposed to twice (which could be negated by the hardware RAID controller)
Edit: Added parameter to clarify that only one single RAID array is desired